Fluid, Electrolyte & Acid- Base Balance
Fluid, Electrolyte & Acid-
Base Balance
Body Fluids
Your body is 66% water
Not evenly distributed – separated into
compartments
Able to move back and forth thru the cell
membranes to maintain an equilibrium
Fluid Compartments
Intracellular fluid – fluid inside cells [ICF]
Extracellular fluid – fluid outside cells
and all other body fluids --- ¼ is plasma
[intravascular fluid], remaining ¾ is
interstitial fluid. Small amount is
localized as CSF, serous fluid, synovial
fluid, humors of eye & endo/perilymph of
ears
Edema
Condition in which fluid accumulates in
the interstitial compartment. Sometimes
due to blockage of lymphatic vessels or
by a lack of plasma proteins or sodium
retention
Fluid Balance
Amount in = amount out
Average daily intake is 2500 ml [ fluids,
food and metabolic water]
Average daily output is 2500 ml [ urine,
feces, perspiration, insensible
perspiration]
What can throw off these numbers?
Electrolyte Balance
Def: - concentration of individual electrolytes in the body fluid compartments is normal and remains relatively constant.
Electrolytes are dissolved in body fluids
Sodium predominant extracellular cation, and chloride is predominant extracellular anion. Bicarbonate also in extracellular spaces
Electrolyte Balance
Potassium is the predominant intracellular cation and phosphates are the predominant intracellular anion
Cations are actively reabsorbed, anions passively follow by electrochemical attraction
Aldosterone works at kidney tubules to regulate sodium & potassium levels
Electrolyte Balance
Because of sodium and potassium
influence, water will move between
compartments
Example: if high [sodium], then water
will move from intracellular space to
extracellular space due to osmotic
pressure
Balance of other Electrolytes
Calcium – hypercalcemia / hypocalcemia
Magnesium – hypermagnesemia/
hypomagnesemia
Phosphate – hyperphosphatemia/
hypophosphatemia
Chloride – hyperchloremia/
hypochloremia
Acid - Base Balance
Blood - normal pH of 7.2 – 7.45
< 7.2 = acidosis > 7.45 = alkalosis
3 buffer systems to maintain normal
blood pH
1. Buffers
2. Removal of CO2 by lungs
3. Removal of H+ ions by kidneys
Buffers
Protein Buffer Systems
Amino Acid buffers
Hemoglobin buffers
Plasma Protein buffers
Phosphate Buffer Systems
Carbonic Acid – Bicarbonate Buffer
System
Maintenance of Acid-Base
Balance
Respiratory System: removal of CO2 by
lungs – stabilizes the ECF, has direct
effect on Carbonic Acid – Bicarbonate
Buffer System
Urinary System: removal of H+ ions by
kidneys
Disturbances to Acid-Base
Balance
Respiratory Acidosis
Respiratory Alkalosis
Metabolic Acidosis [ lactic acidosis,
ketoacidosis]
Metabolic Alkalosis
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